The present invention relates to an apparatus for, and a method of, constructing a tunnel, gallery or the like hereinafter collectively referred to as a tunnel.
Various forms of apparatus are known for constructing tunnels underground. One form of apparatus, with which the invention is mainly concerned, employs a drive or cutting shield composed of elongate members or plates supported in side-by-side relationship around the tunnel so as to contact the wall thereof at least over the roof and side zones. These members are mounted on a rigid frame and are moved, usually by hydraulic rams, to attack a working face.
As the tunnel driving progresses the frame is moved up to follow the advanced members. In other constructions the drive shield is in the form of a continuous cylinder advanced by rams rather than separate members. Hitherto, various methods have been employed to support the tunnel wall behind the drive shield or its frame. One method which is often employed is to install pre-fabricated lining sections end-to-end as the driving progresses. Although this method is quite successful, the tunnel wall exposed by the shifting of the frame usually remains upsupported for some time until the appropriate lining sections can be placed in position. To overcome this problem other systems have been adopted which employ some form of temporary support for the exposed tunnel wall. However, this necessitates extra equipment and often involves a considerable extension in the overall length of the apparatus and this in turn creates additional problems particularly in that the overall progress of constructing the tunnel may be slowed down.
Examples of these known forms of apparatus are disclosed in U.S. Pat. Nos. 3,733,835 and 3,350,889 and in German Patent specification No. 1,534,670.
A general object of this invention is to provide an improved apparatus for and method of constructing a tunnel.
A further object of the invention is to provide an apparatus in which the tunnel lining installed behind the drive shield does not need to take up the forces involved in driving and which can thus proceed independently.
Another object of the invention is to provide an apparatus wherein the guidance and support of the members of the drive shield by the frame is supplemented by additional means.
A further objective is to provide apparatus which will enable the tunnel wall exposed behind the drive shield to be adequately sealed and supported as soon as it becomes accessible.
These objectives should be fulfilled as far as possible in an apparatus of moderate length which is relatively simple and economic.